The present invention relates in general to a mobile communication system. More particularly, the invention relates to a mobile communication system in which the communication is carried out among a line switched mobile communication system, a packet switched mobile communication system and a line switched public switch.
In recent years, the Internet has rapidly come into wide use. The data communication in the Internet is carried out in the form of the IP packet which is obedient to the Internet Protocol (IP) defined in RFC791.
On the other hand, the mobile communication service has also rapidly developed. The mobile communication system has a radio section between a portable terminal and a base station, and a network section which is constituted by accommodation equipment for accommodating therein a base station, a switch, a database for subscriber management, and the like. In the specification of the present application, the network section will hereinafter be referred to as xe2x80x9cthe ground networkxe2x80x9d. In the mobile communication system, the data communication traffic has been rapidly increased, and the discussion is actively carried out with respect to the data transfer in accordance with the IP in the ground network of the mobile communication system. At the present time, in the mobile communication, the voice communication in the ground network is carried out in accordance with the line switching system. With respect to the fact that the signal relating to the voice is transferred in the form of the IP packet in accordance with the packet communication system, the discussion is also actively carried out, and the cost merit due to the realization of the IP of the internal network is expected.
As for prior art of disclosing the mobile communication system which is obedient to the packet communication system, there is 3GPP2 (3rd Generation Partnership Project 2) SC.P000X (Citation 1). This mobile communication system is shown in FIG. 1. In FIG. 1, reference numeral 100 designates a mobile terminal which is accommodated in the mobile communication system through a radio channel. Reference numeral 104 designates a base station which is adapted to communicate with the mobile terminal 100 through the radio channel. The base station 101 is connected to an MSC server 102 through a communication channel. The MSC server 102 includes: the function of converting a voice call received from the base station 101 into the IP packet to send the IP packet thus obtained to an IP network 103; the function of converting the IP packet received from the IP network 103 into the voice call to send the voice call thus obtained to the base station 101; and the function of communicating with a Home Location Register (HLR) 104 for managing the position information of the mobile terminal to acquire the position information of the mobile terminal. Reference numeral 105 designates a Call Agent (CA) which is connected to the IP network 103 and a Public Switches Telephone Network (PSTN) 107 through communication lines, respectively, and which is adapted to convert the IP packet received from the IP network 103 and a call control signal received from the PSTN 107 into each other to carry out the relay. Reference numeral 106 designates a Media Gateway (MG) for converting the IP packet received from the IP network 103 and the voice signal received from the PSTN 107 into each other to carry out the relay. Also, reference numeral 108 designates a fixed telephone which is connected to the PSTN 107 through the communication line.
In the above-mentioned prior art, the IP packet is transferred through the inside of the mobile communication system, whereby the communication is carried out between the mobile terminal 100 and the fixed telephone 108. The CA 105 and the MG 106 are provided between the PSTN 107 of the line switching system and the IP network 103. The CA 105 and the MG 106 are electrically connected to each other by carrying out the signal conversion.
In addition, as for another prior art mobile communication system, there is the mobile communication system which is described in JP-A-2000-278737 (Citation 2) and which is adapted to carry out suitably the switching between the public mode and the private mode in accordance with the position of the portable communication terminal, in particular, the digital cordless telephone terminal which also serves as a PHS. Now, by the public mode is meant the mode in which the information communication is carried out through the base station as the terminal for sending/receipt installed for the public use and which is used when the mobile communication terminal is independently used in the destination of going out. On the other hand, by the private mode is meant the mode in which a specific telephone installed in a home or the like is used as the parent telephone, and the information communication is carried out through this parent telephone and which is used when the child telephone of a specific telephone is used as the mobile communication terminal in a home.
The above-mentioned mobile communication system is shown in FIG. 16. In FIG. 16, reference numeral 1601 designates a digital cordless telephone terminal which also serves as a PHS. Reference numeral 1602 designates a public base station which is adapted to accommodate therein the terminal 1601 having the public mode. Reference numeral 1603 designates a private base station which is adapted to accommodate therein the terminal 1601 having the private mode. Reference numeral 1604 designates a mobile communication system which is connected to the public base station 1602. Reference numeral 1605 designates a telephone network which is connected to the private base station 1603. Reference numeral 1606 designates a normal telephone terminal which is connected to the communication system 1605. Reference numeral 1607 designates position data which is present in the inside of the mobile communication system 1604 and in which the position information of the terminal 1601 is accumulated.
In this communication system, in the system for connecting the arrival-of-the-call using the position data 1607, when a user of a portable telephone is returning home, at a time point when he/she judges that he/she can communicate with the private base station 1603 in his/her home, he/she sends the request to delete the position information of himself/herself in the position data 1607 in the inside of the mobile communication system 1604 or the request to carry out the redirection of arrival-of-the-call. By carrying out the deletion of the position registration, the useless operation of the arrival-of-the-call is not carried out from the public base station 1602 for the request to carry out the communication from the telephone terminal 1606 to the terminal 1601. If the redirection of arrival-of-the-call is set, then this redirection is made arrive at the user-desired communication terminal.
In addition, as for a conventional example of the format with which the call control signal of the line switching system which is required for the mobile communication and the IP packet are converted into each other, there is xe2x80x9cSS7SCCP-User Adaptation Layerxe2x80x9d (Citation 3) as the Internet Draft of the IETF (Internet Engineering Task Force). As described in page 5 of this document, there is proposed the architecture for mapping Transaction Capabilities Application Part (TCAP) as the call control signal of the line switching system required for the mobile communication on the IP packet.
As described above, it is discussed that in the ground network of the mobile communication system, the line switching network is made proceed to the IP network. The present inventors found out that when making the line switching network proceed to the IP network, the following problem arises. That is, since it takes a lot of time to complete such proceeding, it is conceivable that when carrying out the proceeding, the line switching network and the IP network co-exist in the above-mentioned ground network. In this case, for example, the case where an accommodation equipment for accommodating therein the radio base station which is adapted to communicate with a portable terminal is connected to the line switching network, and the case where the accommodation equipment is connected to the IP network may be present depending on the area in which the portable terminal is used. Therefore, it is necessary to judge whether the portable terminal is connected to the line switching network or the IP network.
In the Citation 1 and the Citation 3, the discussion in the case as described above is not made. In addition, the mobile communication system described in the Citation 2 must be mounted with the function of judging whether or not the mobile terminal 1 can communicate with the private base station, and the function that the mobile terminal 1 sends the request to delete the position information of itself or the request to carry out the redirection of arrival-of-the-call.
In a communication system which an embodiment of the present invention discloses, a communication relay system which is connected to a line switched mobile communication system which is adapted to accommodate therein mobile terminals through radio channels, a packet switched mobile communication system which is adapted to accommodate therein the mobile terminals through radio channels, and a public switch relays the communication between the line switched mobile communication system and the packet switched mobile communication system, or the communication among the line switched mobile communication system and the packet switched mobile communication system, and the public switch. The above-mentioned communication relay system, when the request of the connection to a portable terminal has been made, judges whether the portable terminal is accommodated either in the line switched mobile communication system or in the packet switched mobile communication system. The computers which are adapted to manage the position information of the portable terminals which are accommodated in the line switched mobile communication system and the packet switched mobile communication system, respectively, are provided in the line switched mobile communication system and the packet switched mobile communication system, respectively. When the portable terminal as the destination of the connection is accommodated in the line switched mobile communication system, the communication relay system inquires the computer which is provided in the line switched mobile communication system and which is adapted to manage the position information of the position information of that portable terminal, while the portable terminal as the destination of the connection is accommodated in the packet switched mobile communication system, inquires the computer which is provided in the packet switched mobile communication system and which is adapted to manage the position information of that portable terminal.
The details of the communication system disclosed in the present application will be described later.